/***************************************************************************
 *  ArithmeticFunctionSet.cs
 *
 *  Copyright (C) 2007 Novell, Inc.
 *  Written by Aaron Bockover <abockover@novell.com>
 ****************************************************************************/

/*  THIS FILE IS LICENSED UNDER THE MIT LICENSE AS OUTLINED IMMEDIATELY BELOW: 
 *
 *  Permission is hereby granted, free of charge, to any person obtaining a
 *  copy of this software and associated documentation files (the "Software"),  
 *  to deal in the Software without restriction, including without limitation  
 *  the rights to use, copy, modify, merge, publish, distribute, sublicense,  
 *  and/or sell copies of the Software, and to permit persons to whom the  
 *  Software is furnished to do so, subject to the following conditions:
 *
 *  The above copyright notice and this permission notice shall be included in 
 *  all copies or substantial portions of the Software.
 *
 *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
 *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
 *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
 *  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 
 *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 
 *  FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 
 *  DEALINGS IN THE SOFTWARE.
 */

using System;

namespace SExpEngine
{
    public class ArithmeticFunctionSet : FunctionSet
    {
        public enum ArithmeticOperation
        {
            Add,
            Subtract,
            Multiply,
            Divide,
            Modulo
        }

        public virtual TreeNode OnPerformArithmetic(TreeNode [] args, ArithmeticOperation operation)
        {
            double result = 0.0;
            bool as_int = true;
            
            for(int i = 0; i < args.Length; i++) {
                TreeNode arg = Evaluate(args[i]);
                
                if(arg is IntLiteral || arg is DoubleLiteral) {
                    double arg_value;
                    
                    if(arg is DoubleLiteral) {
                        as_int = false;
                        arg_value = (arg as DoubleLiteral).Value;
                    } else {
                        arg_value = (int)(arg as IntLiteral).Value;
                    }
                    
                    if(i == 0) {
                        result = arg_value;
                        continue;
                    }
                    
                    switch(operation) {
                        case ArithmeticOperation.Add:
                            result += arg_value;
                            break;
                        case ArithmeticOperation.Subtract:
                            result -= arg_value;
                            break;
                        case ArithmeticOperation.Multiply:
                            result *= arg_value;
                            break;
                        case ArithmeticOperation.Divide:
                            result /= arg_value;
                            break;
                        case ArithmeticOperation.Modulo:
                            if(!(arg is IntLiteral)) {
                                throw new ArgumentException("Modulo requires int arguments");
                            }
                            
                            result %= (int)arg_value;
                            break;
                    }       
                } else {
                    throw new ArgumentException("arguments must be double or int");
                }
            }
            
            return as_int ? 
                ((TreeNode)new IntLiteral((int)result)) : 
                ((TreeNode)new DoubleLiteral(result));
        }
        
        [Function("add", "+")]
        public virtual TreeNode OnAdd(TreeNode [] args)
        {
            TreeNode first = Evaluate(args[0]);
            
            if(first is StringLiteral) {
                return StringFunctionSet.ConcatenateStrings(Evaluator, args);
            }
        
            return OnPerformArithmetic(args, ArithmeticOperation.Add);
        }
        
        [Function("sub", "-")]
        public virtual TreeNode OnSubtract(TreeNode [] args)
        {
            return OnPerformArithmetic(args, ArithmeticOperation.Subtract);
        }
        
        [Function("mul", "*")]
        public virtual TreeNode OnMultiply(TreeNode [] args)
        {
            return OnPerformArithmetic(args, ArithmeticOperation.Multiply);
        }
        
        [Function("div", "/")]
        public virtual TreeNode OnDivide(TreeNode [] args)
        {
            return OnPerformArithmetic(args, ArithmeticOperation.Divide);
        }
        
        [Function("mod", "%")]
        public virtual TreeNode OnModulo(TreeNode [] args)
        {
            return OnPerformArithmetic(args, ArithmeticOperation.Modulo);
        }
        
        [Function("++")]
        public virtual TreeNode OnIncrement(TreeNode [] args)
        {
            return IntegerUpdate(args, 1);
        }
        
        [Function("--")]
        public virtual TreeNode OnDecrement(TreeNode [] args)
        {
            return IntegerUpdate(args, -1);
        }
        
        private TreeNode IntegerUpdate(TreeNode [] args, int value)
        {
            TreeNode variable_node = (FunctionNode)args[0];
            TreeNode result = Evaluate(variable_node);
            TreeNode new_result = new IntLiteral(((IntLiteral)result).Value + value);
            
            FunctionFunctionSet.VariableSet(Evaluator, args[0], new_result);
            
            return new_result;
        }
    }
}
